Fred, Tim: Wilkosz shows a weak hand, 5-5, at least one major. Fred: Current version of "standard" Polish Club (wj2005, designed by person/committee) uses Multi 2♦ (only weak in a major) + 2 ♥ as 5♥-5 other and 2♠ as 5♠-5 minor. Previous version (wj2000, designed by poll) uses Wikosz 2♦ + "normal" 2M (6+). Quote from end of introduction of WJ2005 book, english version: ** either 12-17 with 5+ ♦. 12-17 with any 4441 with 4♦. 12-14 with 4♦ and 5♣. Even Matula's book (english version, 1994) have the same set of 2-level openings as an alternative in an Appendix named "A new approach to two-level openings", which starts . So, this particular change seems to be regulations driven.